The present invention relates to a storage system, and more specifically, to depopulation of storage ranks.
High-end storage systems use virtualization to provide advanced features such as on demand support. In these storage systems, physical storage resources such as physical disk drives can be virtualized into ranks, extents, extent pools and logical volumes. A rank is normally created based on a group of physical disk drives which have been formatted into one Redundant Array of Inexpensive Disks (RAID) type. The available space of a rank is divided into extents of same size. All the extents from a set of ranks are formed into an extent pool. A logical volume is composed of a set of extents from one extent pool. The logical volumes are represented to hosts and servers in such a way that the hosts and servers see the logical volumes as if they were physical storage resources such as physical disk drives.
Rank depopulation is a method of migrating all the data from the selected ranks to other ranks in the same storage pool so that the depopulated ranks can be freed and be ready for use in other storage pools for resource reconfiguration. Storage System often supplies tools to help users do such task. The method normally migrates the data from the selected ranks sequentially, extent by extent. Such operation often takes hours or even days to finish in real product environment when depopulating large capacity ranks.